Blade and motor carrier with height/angle adjustment mechanism

ABSTRACT

A machine tool has a work table which defines a working surface and has a cutting tool which is attached to and movable with respect to the work table. The cutting tool extends through a removable throat plate. An integral arbor wrench is provided which is accessible when the throat plate is removed. The wrench is designed to engage the arbor shaft to facilitate tool changing by preventing rotation of the arbor shaft. The wrench is also designed to not allow reassembling of the throat plate when the wrench is in engagement with the arbor shaft.

This is a division of U.S. application Ser. No. 08/663,538, filed Jun.17, 1996, now U.S. Pat. No. 5,875,698.

FIELD OF THE INVENTION

The present invention relates to a saw blade height/angle adjustmentmechanism. More particularly, the present invention relates to a motorcarrier for a table saw which provides a unique height/angle adjustmentmechanism for a saw blade attached to the powered shaft of the motor.

BACKGROUND OF THE INVENTION

A typical table saw includes a base which supports a generally flattable top having a longitudinally extending slot and a pair of siderails extending along opposite sides of the table top generallyperpendicular to the slot. The side rails are utilized for mounting arip fence assembly to assist in positioning an article to be cut inrelation to a cutting tool. A motor is mounted beneath the table top andthe cutting tool, which may be a circular saw blade, is mounted forrotation with the powered output shaft of the motor. When the cuttingtool is mounted directly to the shaft of the motor, or if the cuttingtool is mounted to a transmission powered by the motor, the mounting ofthe motor and/or transmission is provided with adjustments whichselectively position the cutting tool to extend through the slot in thetable top. One adjustment for the motor and/or transmission determinesthe amount of the cutting tool which extends through the slot to controlthe depth of cutting. Another adjustment for the motor and/ortransmission determines the angle of the cutting tool with respect tothe table top to control the bevel angle or the angle of cutting. Thecutting tool is thus positioned to project upwardly through the slot andis rotated by the motor with both the height of the cutting tool withrespect to the table top and the angle of the cutting tool with respectto the table top being determined by the mounting mechanism for themotor and/or transmission. Cutting of the workpiece is normallyaccomplished by moving the workpiece longitudinally through the rotatingcutting tool.

Machine tools are used for cross cutting (transverse cutting to thelength of the workpiece), miter cutting (at an angle to the length ofthe workplace) and rip cutting (longitudinal cutting along the length ofthe workplace). For cross cutting and miter cutting, an angularly andlaterally adjustable fixture or fence is used which positions theworkplace perpendicular to or at the desired angle relative to thecutting tool. For rip cutting, a separate rip fence assembly is mountedon the side rails and positioned at a pre-selected distance from thecutting tool in order to perform the longitudinal or rip cuttingoperation on the workpiece.

When performing a cross cutting operation, a miter cutting operation ora rip cutting operation, it is advantageous to have the ability tocontrol the depth of cut. This is accomplished by moving the saw bladegenerally perpendicular to the table top to change the amount of thecutting tool which extends through the table top. In addition, certainapplication will require the addition of a bevel angle during theparticular cutting operation whether it be cross cutting, miter cuttingor rip cutting. The introduction of a bevel angle is accomplished byangulating the cutting tool with respect to the table top or angulatingthe table top with respect to the cutting tool.

Manufacturers of power tool equipment have developed a variety ofmechanisms which provide for both the height adjustment and the angularadjustment of the cutting tool with respect to the table top when thepower tool is a direct drive power tool. The continued development ofthe height and angle adjustment mechanisms is directed towards systemswhich rigidly hold the cutting tool at the pre-selected position whilemaintaining a simple and easily actuated system for moving the cuttingtool to other desired positions. The system should be as rigid aspossible to provide accuracy during the cutting operation but shouldmaintain an easily actuated mechanism to facilitate the changes requiredby the user. The system should provide the above advantages whilekeeping both the weight of the system and the costs to manufacture thesystem at a minimum.

SUMMARY OF THE INVENTION

The present invention provides the art with a height and angleadjustment mechanism for a cutting tool. The mechanism includes a motorand arbor support plate which is pivotably secured to the bottom of thework surface of the cutting tool by a pair of brackets to provide forthe angular adjustment. A transmission or gear case is slidablyconnected to the support plate to provide for the height adjustment. Themotor, arbor and cutting tool are attached to the gear case. The cuttingtool height is adjusted by way of a crank and a threaded rod, upon whicha rod follower is movably threaded. The rod follower is connected to aheight adjusting lever for slidably moving the gear case and thus themotor, arbor and cutting tool upwardly and downwardly depending upon thedirection in which the crank is rotated. The cutting tool angularposition is adjusted by pivotably moving the support plate to change theangle of the blade. The angular position of the support plate is lockedin position by a locking bar which extends through an arcuate slot inthe front of the cutting tool base across the support plate and througha similar arcuate slot in a bracket attached to the rear of the cuttingtool base. A cam lever mechanism is positioned outward of the front ofthe cutting tool base such that when the cam lever is pivoted to itslocked position, the locking bar is pulled forwardly compressing andfrictionally locking the support plate between the bracket and the frontof the cutting tool base. The flexibility of the locking rod and thebracket provides the ability for the compressing of the support plate.The locking of the support plate to both the front and rear of the baseprovides increased rigidity to the system once it is locked.

Other advantages and objects of the present invention will becomeapparent to those skilled in the art from the subsequent detaileddescription, appended claims and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings which illustrate the best mode presently contemplatedfor carrying out the present invention:

FIG. 1 is a perspective view of a table saw incorporating a uniqueheight and angular adjustment mechanism in accordance with the presentinvention;

FIG. 2 is a cut-away perspective view of the table saw shown in FIG. 1with a portion of the upper surface of the work table removed and thebase cut away to illustrate the adjustment mechanisms in accordance withthe present invention;

FIG. 3 is a cut-away perspective view similar to FIG. 2 with the motor,saw blade and gear case removed to illustrate the angular adjustmentmechanism in accordance with the present invention;

FIG. 4 is an exploded perspective view of the angular adjustmentmechanism shown in FIG. 3;

FIG. 5 is a side view of the support plate shown in FIGS. 1-3 with themotor, saw blade and mounting plate included to illustrate the heightadjustment mechanism in accordance with the present invention;

FIG. 6 is an end view of the height adjustment mechanism shown in FIG.5;

FIG. 7 is an exploded perspective view of the pivot quadrantsincorporated into the angular adjustment mechanism of the presentinvention;

FIG. 8 is a schematic cross-sectional view taken through the gear caseillustrating the assembly of the gear case to the support plate;

FIG. 9 is an exploded perspective view of the height adjustmentmechanism shown in FIGS. 5-6;

FIG. 10 is a side view illustrating the arbor locking mechanism inaccordance with the present invention in the unlocked position;

FIG. 11 is a side view similar to FIG. 10 but showing the lockingmechanism in the locked position; and

FIG. 12 is a side view schematically illustrating an adjustmentmechanism for the bevel adjustment system of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings in which like reference numerals designatelike or corresponding parts throughout the several views, there is shownin FIG. 1 a machine tool which is designated generally by the referencenumeral 10 incorporating a height/angle adjustment mechanism for thecutting tool and motor carrier in accordance with the present invention.While the height/angle adjustment mechanism of the present invention isbeing illustrated for exemplary purposes as being used in conjunctionwith machine tool 10 in the form of a table saw, it is within the scopeof the present invention to incorporate the height/angle adjustmentmechanism of the present invention into any type of machine tool whichutilizes a cutting tool.

Referring to FIG. 1, machine tool 10 comprises a base 12 which supportsa generally rectangular work table 14 defining a working surface 16.Work table 14 includes a throat plate 18 which includes an elongatedslot 20 through which a circular saw blade 22 protrudes. Saw blade 22 iscapable to being adjusted for angularity with respect to working surface16 by an angle or bevel adjustment mechanism 24 as well as being capableof being adjusted for depth of cut by a height adjustment mechanism 26.Machine tool 10 is illustrated as a portable table saw which is easilymovable from one job site to another. Table saw 10 can easily be pickedup and carried utilizing work table 14 as the supporting locations whenit becomes necessary to lift and carry table saw 10 from one job site toanother.

Referring now to FIG. 2, table saw 10 is illustrated with workingsurface 16 of work table 14 partially removed and a portion of base 12cut away. Circular saw blade 22 is rotated by a motor assembly whichincludes a motor 28 and a gear case 30, Motor 38 powers saw blade 22through gear case 30. Bevel adjustment mechanism 24 adjusts the angularposition of saw blade 22 by pivoting saw blade 22, motor 28 and gearcase 30. Height adjustment mechanism 26 adjusts the cutting depth of sawblade 22 by vertical movement of saw blade 22, motor 28 and gear case30.

Referring now to FIGS. 2 and 3, bevel adjustment mechanism 24 comprisesa pair of pivot quadrants 32, a support plate 34, and a locking system36. Each pivot quadrant 32 is attached to a plurality of bosses 38extending from the bottom of work table 14 using a plurality of bolts40. Each pivot quadrant 32 is designed to pivot around a center which islocated on working surface 16 of work table 14 coincident with the planeof saw blade 22. Thus, the axis for pivoting support plate 34 lies onworking surface 16 and extends through the plane of saw blade 22 whensaw blade 22 is generally perpendicular with working surface 16. Asshown in FIG. 7, pivot quadrant 32 is comprised of a support bracket 42,a pivot bracket 44 and a retaining strap 46. Support bracket 42 is anL-shaped bracket which defines a plurality of holes 48 to facilitate theattachment of pivot quadrant 32 to work table 14 on one leg of the L Theopposite leg of the L defines an arcuate slot 50 which controls thepivotal movement of pivot bracket 44 and locates the center of thepivoting at working surface 16 of work table 14. Pivot bracket 44extends between support bracket 42 and support plate 34 and defines aplurality of holes 52 at one end to facilitate the attachment of supportplate 34. The opposite end of pivot bracket 44 defines a stamped arcuateprotrusion 54 which mates with slot 50 to control the pivoting of pivotbracket 44. Protrusion 54 is formed out of the material of pivot bracket44 and this forming operation defines an arcuate slot 56 once protrusion54 has been formed. Retaining strap 46 extends across pivot bracket 44and is attached to support bracket 42 to maintain the engagement ofprotrusion 54 with slot 50. Retaining strap 46 defines a formedprotrusion 58 which extends into slot 56 to both guide the pivotalmovement of pivot bracket 44 and to act as a stop to limit the pivotalmovement of pivot bracket 44.

Referring now to FIGS. 3 and 4, support plate 34 is a shallow drawnplate which is attached to pivot quadrants 32. Support plate 34 isdesigned to support both height adjustment mechanism 26 and lockingsystem 36. Locking system 36 comprises a bearing block 60, a locking rod62, a locking arm 64, a bearing block cam 66, a locking arm cam 68 and areturn spring 70. Bearing block 60 is a curved member which is attachedto a bracket 72 which is in turn attached to support plate 34. Bearingblock 60 thus pivots with support plate 34 and bearing block 60 extendsthrough an arcuate slot 74 in the front face of base 12. While thepivotal movement of support plate 34 moves bearing block 60 within slot74, it should be understood that the movement of support plate 34 iscontrolled by pivot quadrants 32 and that a clearance will always existbetween bearing block 60 and slot 74.

Locking rod 62 extends across support plate 34 and through bracket 72and bearing block 60 in the front of support plate 34 and through abracket 76 and a bracket 78 located at the rear of support plate 34.Bracket 76 is attached to support plate 34 and defines an aperture foraccepting and guiding locking rod 62. Bracket 78 is attached to worktable 14 and it defines an arcuate slot 80 which accepts locking rod 62and allows for the pivotal movement of support plate 34. While thepivotal movement of support plate 34 moves locking rod 62 within slot80, it should be understood that the movement of support plate 34 iscontrolled by pivot quadrants 32 and that a clearance will always existbetween locking rod 62 and slot 80. Once locking rod 62 has beeninserted through brackets 76 and 78, an adjustment device in the form ofa washer 82 and a nut 84 is assembled to locking rod 62 to provideadjustment for locking system 36. The front end of locking rod 62extends through bearing block 60 and through a D-shaped embossment 86which is an integral part of bearing block 60. Locking arm 64 isassembled over the end of locking rod 62 and secured to locking rod 62using a hardened washer 88, a thrust bearing 90, a hardened washer 92and a nut 94 threadingly received on locking rod 62 as shown in FIG. 4.

Bearing block cam 66 and locking arm cam 68 are disposed between lockingarm 64 and bearing block 60. D-shaped embossment 86 extends from bearingblock 60 through slot 74 in the front face of base 12. Bearing block cam66 includes a D-shaped aperture which mates with embossment 86 and cam66 is positioned such that the front face of base 12 is sandwichedbetween bearing block 60 and bearing block cam 66. The engagement of theD-shaped aperture of cam 66 with D-shaped embossment 86 prohibits therotational movement of cam 66 with respect to bearing block 60. The faceof cam 66 opposite to the front surface of base 12 defines a cammingsurface 96 which reacts with locking arm cam 68 to activate lockingsystem 36.

Locking arm 64 defines a D-shaped embossment 98 which mates with aD-shaped aperture extending through locking arm cam 68 such that lockingarm cam 68 pivots with locking arm 64 when locking arm 64 pivots onlocking rod 62. The face of cam 68 opposite to locking arm 64 defines acamming surface 100 which mates with camming surface 96 on cam 66 suchthat pivoting motion of locking arm 64 with respect to locking rod 62will cause longitudinal movement of locking rod 62 to activate lockingsystem 36. Return spring 70 is disposed on locking rod 62 between an ear102 formed on locking rod 62 and bearing block 60 in order to urgelocking rod 62 towards the rear of base 12 or towards bracket 78.Locking rod 62 is shown with an additional ear 102 on the opposite sideof return spring 70 to capture spring 70 in the unassembled condition oflocking rod 62. The additional ear 102 requires that the aperture inbearing block 60 which accepts locking rod 62 be provided with a slot(not shown) to accept the additional ear 102. In this arrangement, theengagement of the additional ear 102 with the slot in bearing block 60will prohibit any rotational movement of locking rod 62.

When camming surface 96 is aligned with camming surface 100, pivoting ofsupport plate 34 and thus saw blade 22 and motor 28 is permitted. Thebiasing of locking rod 62 towards the rear of base 12 causes embossment98 to bottom against embossment 86. In this condition, there is aclearance created between camming surface 96 and camming surface 100 aswell as a clearance created between bracket 76 and bracket 78. Theseclearances allow for a smooth pivoting of support plate 34 and thus asmooth angular adjustment for saw blade 22. The pivoting of supportplate 34 is controlled by pivot quadrants 32 while bearing block 60moves within slot 74 in the front face of base 12 and locking rod 62moves within slot 80 in bracket 78. When the desired angle of saw blade22 is obtained, locking system 36 is activated by pivoting locking arm64 on locking rod 62 which rotates cam 68 with respect to cam 66.Camming surface 100 is cammed away from camming surface 96 causinglongitudinal movement of locking rod 62. The longitudinal movement oflocking rod 62 compresses support plate 34 between bracket 78 and thefront face of base 12 due to washer 82 and nut 84 engaging bracket 78and bearing block cam 66 engaging the front surface of base 12. Theflexibility of locking rod 62 due to a center off-set area 104 and theflexibility of bracket 78 permit the compression of support plate 34.The adjustment for locking system 36 is provided for by nut 84.

Referring now to FIGS. 2, 5, 6 and 9, height adjustment mechanism 26comprises a pivot link 110, a biasing spring 112, a follower nut 114, aheight adjustment screw 116 and a crank handle 118 which function tomove saw blade 22, motor 28 and gear case 30 longitudinally with respectto support plate 34.

Support plate 34 defines a generally rectangular opening 120 withinwhich gear case 30 is located. Located adjacent to and extendinggenerally the entire length of opening 120 are a pair of formed ribs 122which provide stiffness to support plate 34. Gear case 30 includes ahousing 124 disposed on one side of support plate 34 and a cover 126disposed on the opposite side of support plate 34. Cover 126 is securedto housing 124 by a plurality of bolts 128 such that support plate 34 issandwiched between cover 126 and housing 124. Gear case 30 includes apair of longitudinally extending surfaces 130 which engage the opposingsides of opening 120 to guide the movement of gear case 30 withinopening 120. Motor 28 is attached to housing 124 and includes anarmature shaft 132 having a pinion 134 which meshes with an output gear136 which is rotatably supported within gear case 30. The output gearincludes an arbor shaft 138 which provides for the attachment of sawblade 22. Thus, when motor 28 is powered, armature shaft 132 and pinion134 rotate which rotates output gear 136 and arbor shaft 138 which inturn rotates saw blade 22.

Referring now to FIG. 8, the accurate positioning of saw blade 22 isrequired in order to provide accurate cuts. In order to accuratelyposition saw blade 22, the front face, or the face adjacent saw blade22, of support plate 34 is defined as a datum face. Cover 126 isprovided with a plurality of accurately machined pads 140 whichaccurately position cover 126 and thus saw blade 22 with respect tosupport plate 34. Machined pads 140 are biased against the datum face onsupport plate 34 by a plurality of elastomeric springs 142 each of whichis disposed within an aperture 144 defined by housing 124. A lowfriction wear pad 146 is disposed between each elastomeric spring 142and support plate 34 to facilitate the movement of gear case 30 withinopening 120. Thus, gear case 30, motor 28 and saw blade 22 movelongitudinally within opening 120 guided by surfaces 130 with gear case30 being biased against the datum face of support plate 34 byelastomeric springs 142. As shown in FIGS. 2 and 5, cover 126 includesan extension 148 which can be utilized for supporting a splitter and/orguard mechanism for table saw 10 if desired. The mounting of thesplitter and/or guard mechanism on cover 126 allows the components totravel with saw blade 22 during cutting depth and/or angularadjustments.

Referring back to FIGS. 2, 5, 6 and 9, pivot link 110 is pivotablysecured to support plate 34 by an appropriate fastener 150. One arm ofpivot link 110 defines a slot 152 which engages a pin 154 attached togear case 30. The second arm of pivot link 110 defines a slot 156 whichengages follower nut 114. Biasing spring 112 is a tension springpositioned around fastener 150 and is disposed between pivot link 110and a retainer 158. Retainer 158 is attached to follower nut 114 andbiasing spring 112 is positioned such that its spring force biases gearcase 30 towards a downward position. By biasing pivot link 110 in thisdirection, the play between the various components of height adjustmentmechanism 26 can be eliminated. In addition, the biasing load providedby biasing spring 112 is resisted by follower nut 114 and not byadjustment screw 116 as in many prior art table saws.

Height adjustment screw 116 is rotatably secured at one end by a bracket160 which is a separate component or bracket 160 can be formed out ofsupport plate 34. A nylon bushing 162 is disposed between screw 116 andbracket 160 to facilitate the rotation of screw 116 and provide asmoothness of operation. The loading and thus the wear between screw116, bushing 162 and bracket 160 is significantly reduced due to thereaction of spring 112 occurring through follower nut 114 and notthrough screw 116. The opposite end of adjustment screw 116 extendsthrough and is rotatably supported by bearing block 60. The portion ofadjustment screw 116 which extends beyond bearing block 60 is adaptedfor securing crank handle 118 to adjustment screw 116 such that rotationof crank handle 118 causes rotation of adjustment screw 116. Disposedbetween bearing block 60 and bracket 72 of support plate 34 is ahardened washer 164, a powdered metal washer 166, a spring thrust washer168 and a hardened washer 170. Powdered metal washer 166 is secured toadjustment screw 116 by press fitting or other means known in the art.The biasing of spring thrust washer 168 produces frictional resistanceto the rotation of adjustment screw 116 allowing for the accuratepositioning of saw blade 22 and the ability of height adjustmentmechanism 26 to maintain the position of saw blade 22 during the cuttingoperation. The frictional resistance or drag produced by spring thrustwasher 168 maintains the position of adjustment screw 116 and is notaffected by the vibration produced by motor 28 and/or the cuttingoperation. In addition, the biasing produced by spring thrust washer 168removes any play which may exist between the various components ofheight adjustment 26.

Follower nut 114 is threadingly received on a threaded portion 172 ofscrew 116 which is located between bracket 160 and bearing block 60.Follower nut 114 includes a cylindrical finger 174 which extends intoretainer 158, into slot 156 of pivot link 110 and into a slot 176located in support plate 34 to cause the pivoting of pivot link 110 byfollower nut 114. Slot 176 in support plate 34 prohibits rotation offollower nut 114 and tends to guide follower nut 114 as it moves alongscrew 116. In addition, the contact between finger 174 and the edge ofslot 176 provides the reaction point for spring 112. Thus, when crankhandle 118 is rotated, adjustment screw 116 is rotated which causesfollower nut 114 to move longitudinally along threaded portion 172 ofadjustment screw 116. The direction of movement of follower nut 114 willbe determined by the design of threaded portion 172 and the direction ofrotation of crank handle 118. The longitudinal movement of follower nut114 causes pivotal movement of pivot link 110 due to the engagement offinger 174 which engages slot 176. The pivotal movement of pivot link110 causes the longitudinal movement of gear case 30, motor 28 and sawblade 22 due to the engagement of slot 152 with pin 154. Thelongitudinal movement of gear case 30, motor 28 and saw blade 22 setsthe height of saw blade 22 extending through work table 14 and thus thedepth of cut.

Referring to FIGS. 8, 10 and 11, cover 126 of gear case 30 supportsanother unique feature for machine tool 10. One of the problemsassociated with machine tools is the changing of the cutting tool. Sawblade 22 is assembled to arbor shaft 138 and is frictionally held inposition by a pair of washers 180, 182 and an arbor nut 184. Arbor shaft138 includes a pair of flats 186 which accept a wrench in order to stoparbor shaft 138 from rotating when arbor nut 184 is to be loosened ortightened during the changing of saw blade 22. The wrench for engagingflats 186 is normally a separate piece which is easily misplaced whichthen leads to the wedging of a block of wood or other material againstsaw blade 22 to hold arbor shaft 138. The wedging of the block againstsaw blade 22 is both dangerous and leads to unnecessary loading of thebearings supporting arbor shaft 138. The present invention includes alever 188 which is pivotably secured to cover 126. A wrench 190 ispivotably secured to lever 188 and moves within a pocket 192 formed by aridge 194 which is an integral part of cover 126 between an unlockedposition shown in FIG. 10 and a locked position shown in FIG. 11. Aspring 196 biases wrench 190 into its unlocked position.

The unlocked position of wrench 190 is shown in FIG. 10 where wrench 190is disconnected from flats 186 and arbor shaft 138 is free to rotate.The locked position is shown in FIG. 11 where a slot in wrench 190engages flats 186 to prohibit rotation of arbor shaft 138. The end ofwrench 190 engages ridge 194 at both the front of wrench 190 adjacentarbor shaft 138 to provide support for wrench 190 in the locked positionand at the rear of wrench 190 adjacent to lever 188 to provide supportto counteract the torque being allied to arbor nut 184. Lever 188 isaccessible to the operator of table saw 10 through the opening in worktable 14 which accepts throat plate 18. Lever 188 is designed to extendinto the throat plate opening of work table 14 when wrench 190 is in thelocked position and saw blade 22 is in its full upward position as shownin FIG. 11 to prohibit the assembly of throat plate 18 with work table14 while wrench 190 is in the locked position. Once wrench 190 is movedto its unlocked position, lever 188 will be removed from the throatplate opening in work table 14 and throat plate 18 can be assembled towork table 14.

FIG. 12 illustrates a bevel angle stop system for bevel adjustmentmechanism 24. An adjustment cam 200 with a stop cam surface 201 thereonis attached to the front panel of work table 14 at opposite ends of slot74. A protrusion 202 is formed at both ends of bearing block 60. Whensaw blade 22 is positioned at a point perpendicular to working surface16, adjustment cam 200 at the zero degree position is rotated until itsstop cam surface 201 contacts the zero degree protrusion 202 on bearingblock 60. Adjustment cam 200 is tightened in position using a bolt 204to set the zero degree position of saw blade 22. The tightening of bolt204 has a tendency to rotate cam 200 in a clockwise direction. Therotation of the stop cam surface 201 in a clockwise direction urges cam200 into contact with protrusion 202 due to the external spiral shape ofthe stop cam surface 201 to provide an accurate positioning of the bevelangle for saw blade 22. The perpendicularity of saw blade 22 can be setby a square or other means known well in the art. In a similar manner,the 45° position of saw blade 22 with respect to working surface 16 canbe set by a similar adjustment and locking of adjustment cam 200 locatedon the opposite side of slot 74.

While the above detailed description describes the preferred embodimentof the present invention, it should be understood that the presentinvention is susceptible to modification, variation and alterationwithout deviating from the scope and fair meaning of the subjoinedclaims.

What is claimed is:
 1. A cutting machine comprising: a work tabledefining a work surface, said work table having an opening extendingthrough said work surface; a motor assembly mounted to said work tableand including a rotatable arbor shaft driving a cutting device; a throatplate removably disposed in said opening, said throat platesubstantially covering said opening, said throat plate defining anaperture through which said cutting device extends; a lever attached tosaid motor assembly and pivotable between a first and a second position;said lever extending through said opening in said work surface of saidwork table when said lever is in said first position to thereby preventsaid throat plate from being disposed in said opening; a wrench attachedto said lever, said wrench defining a slot which engages said arborshaft to prevent rotation thereof when said lever is in said firstposition, said arbor shaft being free to rotate when said lever is insaid second position.
 2. The cutting machine of claim 1 furtherincluding biasing means for biasing said lever into said secondposition.